Mud motor stators and pumps and method of making

ABSTRACT

A mud motor stator or a pump comprising of a tubular outer portion; a number of lobes extending radially inwardly from the tubular outer portion, at least one of which comprises a skeletal structure and method for producing a mud motor stator or a pump comprising of placing material and bonding the material together in a pattern dictated by the design shape of the stator or pump.

BACKGROUND

Mud motor stators and pumps are in some cases constructed of hardmaterials such as metal and sometimes softer materials faced on themetal for sealing purposes. The overall structure is a helical one withlobes extending toward an axis of the stator which makes them difficultto machine and impossible to adjust properties. Since adjustment canimprove efficiency of mud motors, the art is always receptive toenhancements in manufacturing processes and functional characteristicsof the resulting product.

BRIEF DESCRIPTION

Disclosed herein is a mud motor stator or a pump. The mud motor statoror pump includes a tubular outer portion and a number of lobes extendingradially inwardly from the tubular outer portion, at least one of whichcomprises a skeletal structure.

Also disclosed is a method for producing a mud motor stator or a pumpincluding placing material and bonding the material together in apattern dictated by the design shape of the stator or pump.

Also disclosed is a method for producing a mud motor stator or a pumpincluding creating a computer model of a stator or pump, loading themodel into an additive manufacturing apparatus; and operating theadditive manufacturing apparatus to produce a physical replica of themodel.

Also disclosed is a downhole system including a mud motor stator or apump, the stator or pump being as defined in any prior embodimentincluding a tubular outer portion and a number of lobes extendingradially inwardly from the tubular outer portion, at least one of whichcomprises a skeletal structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The following descriptions should not be considered limiting in any way.With reference to the accompanying drawings, like elements are numberedalike:

FIG. 1 is a schematic perspective view of a stator for a mud motor asdisclosed herein; and

FIG. 2 is an end view of the stator of FIG. 1 illustrating the makeup ofthe stator;

FIG. 3 is an end view similar to FIG. 2 but of an alternate embodiment;

FIG. 4 is a schematic view of an asymmetric lobe pattern;

FIGS. 5, 6 and 7 are alternative surface details; and

FIG. 8 is a schematic representation of a downhole system including thestator or pump as disclosed herein.

DETAILED DESCRIPTION

A detailed description of one or more embodiments of the disclosedapparatus and method are presented herein by way of exemplification andnot limitation with reference to the Figures.

Referring to FIGS. 1 and 2 simultaneously, stator 10 which may be usedin a mud motor or pumps and made part of a downhole system includes atubular outer portion 12 and a number of lobes 14, which may beasymmetric, extending toward an axis of the stator 10. Also visible is asealing material 16 disposed radially inwardly of the stator body 10 andwhich may or may not be disposed symmetrically with the lobes 14. In oneembodiment, the sealing material on the seal side is thicker than it ison the load side. The exact positioning and construction of the lobes 14and material 16 can dramatically affect the function and operation ofthe stator 10 in terms of sealing capability, vibration reduction, poweroutput, mass, and longevity, among other things.

Weight, material cost, and properties such as resilience, compliance,sealing, load bearing, vibration resonant frequencies, etc. are allimportant characteristics of the function of a stator but heretoforehave not been recognized as such and have not been addressed.

As can be seen in FIGS. 1 and 2, the lobes 14 are not configured as arethose of the prior art (solid and sinuous) but rather are configured toprovide a greater rigidity on the load side 18 of each stator lobe 14versus the seal side 20 of each stator lobe 14. Specifically, a skeletalstructure 22 is constructed having, in one embodiment just a hollow 24(Fig.) of the lobe 14 and in another embodiment having a number of ribs26 (FIG. 2), Skeletal structure is defined herein as any configurationof solid portions and open spaces defined between the solid portions toexhibit a framework. The hollow 24 is bounded by an operating portion 28of the lobe 14. In the FIG. 2 embodiment, the ribs 26 extend from onepoint to another point inside the otherwise hollow space bounded by theoperating portion 28 of the lobe 14. As illustrated in FIG. 2, the ribs26 extend from the tubular portion 12 radially inwardly until theyconnect to the operating portion of the lobe 14. Other reinforcingstructure patterns are also contemplated. In some embodiments, the loadside of the lobe 18 follows a contour that is close to the load surfaceof the lobe 14. This makes the sealing material 16 thin at this side ofthe lobe but well supported for high load carrying capability whilestill providing a sealing function. Conversely, the contour at thesealing side of the lobes 14 is left largely unsupported by the skeletalstructure 22. In other embodiments, the lobes are more asymmetric andthe sealing material 16 may have the same thickness throughout. See FIG.4 for a schematic view of an asymmetric lobe pattern. The sealingmaterial 16 often is constructed of rubber though other compoundsincluding metal with adjusted material properties such as density,resilience, etc. is also contemplated herein. In addition, theconfiguration of the lobes 14 whether symmetric or asymmetric may beoptimized to avoid the generation of resonant frequencies during use.

In the FIG. 2 iteration, the ribs 26, (three shown but more or fewercontemplated) are oriented to be substantially normal to the surface ofthe load side 18 of the lobes 14. This structurally provides greatrigidity to the load side of lobe 14 while reducing weight over priorart configurations. As noted, it is contemplated to provide ribs orother structure or shapes in other configurations as well and onepurpose of such is to adjust the compliance of the load side of the lobe14 for applications that may benefit from such.

In FIG. 3, there are no ribs at all but rather merely a hollow 24 withinthe lobe 14. The sealing material 16 is however the same in theembodiment for purposes of comparison to the embodiment of FIG. 2 andtherefore understanding of the concept.

In addition to the structural and weight characteristics of thestructures disclosed and shown, it is also to be appreciated that thevolume between the ribs 26 or the hollow 24 may be employed as a fluidconduit (conveyance and/or cooling) or a conductor conduit (forelectric, hydraulic or optical line).

In addition to the overall shape and structure of the lobes 14 as notedabove, it is also contemplated herein to change the surface condition onthe lobes 14 and the internal surface 30 of the stator body 12.Referring to FIGS. 5, 6 and 7, the surface in some embodiments israndomly roughened, a diamond shaped pattern (FIG. 5), wavy (FIG. 6),having grooves 32 and/or bumps 34 (FIG. 7), etc. for the purpose ofincreasing adhesion of the material 16 that will be disposed thereon aswell as improving the function of the rubber injection process byincreasing adhesion and reducing injection pressure and temperature.

The stator or pump 10 may be created by conventional manufacturingmethods but would be laborious to achieve. Therefore the inventorshereof also note that additive manufacturing or 3D printing is highlysuited to producing all of the features noted above with respect to thevarious alternate embodiments of a stator or pump disclosed herein. Eachof the stator or pump embodiments may be created using one or more ofselective laser melting, direct metal laser sintering, direct metallaser melting, selective laser sintering, electron beam manufacturing,direct laser deposition, cold gas processing, laser cladding, directmaterial deposition, ceramic additive manufacturing, ultrasonic welding,or binder jetting and subsequent sintering, for example in powder bed ornozzle feed or wire feed configurations. The material deposited isbonded together by welding, binding and sintering, etc. Additivemanufacturing processes are known to the art and require no specificdiscussion in connection with this disclosure.

In each of the additive manufacturing processes noted above (or othersfunctioning similarly) the complex shapes represented in the figures areeasily created in the layer by layer or particle by particle approach ofadditive manufacturing processes. In addition to the overall shape asshown, AM also supports the other adjustments discussed above withrespect to density, resilience, compliance, etc. (see above) of thematerial used to make the stator 10, to wit: one of the operatingparameters of the process may be modified to produce a material propertyin a location within the stator 10 that is different than that materialproperty elsewhere in stator 10. For example, the process of melting maybe halted where an opening is to be located. Alternatively oradditionally, the process may be altered to change the density of thebase material in certain areas to cause a feature to be resilient orcompliant.

In order to change properties as noted above, changes in one or moreparameters of the additive manufacturing process used to create thematerial may be made. These changes include but are not limited to:varying the energy applied to the feed material by the energy sourcee.g. laser or electron beam (varying the energy source power includingzero power, varying the energy source focus, varying the energy sourcescanning speed, varying the energy source line spacing) or varying thefeed material itself may be employed. More specifically, with respect toenergy applied, the energy source being employed, whether e.g. 200, 400,1000 W or any other energy source power, may be reduced in power at theselected location to reduce the melting of the powdered (or other type)feed material. Reduction in the amount of melt will change the densityof the manufactured part in locations where melting was reduced oreliminated in the case of zero power (which will simply leave feedmaterial unaltered, e.g. still powdered). Alternatively, one may changethe energy source focus, which also changes the energy applied to thefeed material. Further, another alternative is to change the laserenergy source scanning speed to alter the energy imparted to the feedmaterial in certain locations. Varying the line spacing of the scanningenergy source results in altered porosity or density of the stator 10 inlocations where line spacing diverges from otherwise normal line spacingfor the part. Causing line spacing to become larger will result in alower density and greater porosity of the stator 10 in those areas inwhich line spacing is increased. Each of these will change the degree offusing of the feed material at that location with the surroundingparticles of feed material and hence change the density or porosity ofthe final manufactured product at that location. It is to be understoodthat other material properties such as thermal conductivity, electricalconductivity, magnetism, etc. may also be altered using processes thatchange feed materials.

While reducing energy applied is discussed above it is also important tonote that energy increase can also be useful in achieving specificmaterial properties desired in the Stator 10. Increasing energy sourcepower will tend to vaporize the powdered metal thereby leaving porosity.

Referring back to the other identified method for altering the materialproperties in a stator that does not rely upon energy supplied, the feedmaterial itself may be altered. This may be accomplished by changing thematerial supplied at a feed head for powdered feed material or bychanging the wire composition in a wire feed process. Processes capableof additive manufacturing with different materials include cold gasprocesses, energy source cladding or direct laser deposition, forexample.

Materials contemplated for construction of the stator or pump includefine particles of or a wire including metal and/or metal alloy materialand may optionally further include plastic, ceramic, and/or organicmaterial. More specifically, material may include, for example, cobalt,nickel, copper, chromium, aluminum, iron, steel, stainless steel,titanium, tungsten, or alloys and mixtures thereof, magneticallyresponsive materials, polyetheretherketone (PEEK™), carbon-basedmaterials (e.g., graphite, graphene, diamond, etc.), and/or glass.Specific, nonlimiting examples, of materials that may be employedinclude PA12-MD(Al), PA12-CF, PA11, 18Mar 300/1.2709, 15-5/1.4540,1.4404 (316L), Alloy 718, Alloy 625, CoCrMo, UNS R31538, Ti6AI4V andAlSi10Mg, Alloy 945x, 17-4/1.4542, Alloy 925, CrMnMoN-steel, CoCrAlloys(STELLITE®), CoNiAlloy, MP35 or equivalent, 4140, 4145, WC-Ni, WC-Co,and/or W. Another example of material employed is fine particles ofmetal or metal alloy material intermixed with fine particles of ceramicmaterial, the material being configured to form a metallic-ceramiccomposite material (e.g., a cermet), in which ceramic particles areembedded within a metal or metal alloy matrix, upon melting andcoalescence of the particles of metal and/or metal alloy material. Morespecifically, these materials may be fine particles of cobalt, nickel,iron, steel, stainless steel, or alloys and mixtures thereof intermixedwith fine particles of tungsten carbide, titanium carbide, tantalumcarbide, molybdenum carbide, and other metal-carbide ceramic materials.

Referring to FIG. 8, a downhole system is schematically illustratedhaving a stator or pump as disclosed herein disposed therein. The systemcomprises a string 40 disposed in a borehole 42, the string including astator or pump 10.

Set forth below are some embodiments of the foregoing disclosure:

Embodiment 1

A mud motor stator or a pump comprising a tubular outer portion; anumber of lobes extending radially inwardly from the tubular outerportion, at least one of which comprises a skeletal structure.

Embodiment 2

The stator or pump of any prior embodiment wherein the skeletalstructure consists of an operating portion of the at least one lobe.

Embodiment 3

The stator or pump of any prior embodiment wherein the skeletalstructure comprises one or more ribs.

Embodiment 4

The stator or pump of any prior embodiment wherein the one or more ribsextend to connect to an operating portion of the at least one lobe.

Embodiment 5

The stator or pump of any prior embodiment further including materialproperty changes in areas of the stator constructed of the samematerial.

Embodiment 6

The stator or pump of any prior embodiment wherein the material propertyis compliance or resilience.

Embodiment 7

The stator or pump of any prior embodiment wherein the tubular outerportion and the number of lobes include surfaces and wherein at least aportion of those surfaces is conditioned.

Embodiment 8

The stator or pump of any prior embodiment wherein the surfaceconfiguration is conditioned to exhibit a diamond shaped pattern.

Embodiment 9

The stator or pump of any prior embodiment wherein the surfaceconfiguration is conditioned to be wavy.

Embodiment 10

The stator or pump of any prior embodiment wherein the surfaceconfiguration is conditioned to exhibit at least one of grooves andbumps

Embodiment 11

The stator or pump of any prior embodiment wherein the skeletalstructure is asymmetric and having a load side and a seal side, and asealing material that is thicker at the seal side than it is at the loadside.

Embodiment 12

The stator or pump of any prior embodiment wherein the skeletalstructure is asymmetric and having a load side and a seal side, and asealing material that is the same at the seal side as it is at the loadside.

Embodiment 13

The stator or pump of any prior embodiment wherein the skeletalstructure defines a pathway through the stator for one or more of fluidand conductors.

Embodiment 14

A method for producing a mud motor stator or a pump includes placingmaterial and bonding the material together in a pattern dictated by thedesign shape of the stator or pump.

Embodiment 15

The method of any prior embodiment wherein the bonding is by directmetal laser melting.

Embodiment 16

A method for producing a mud motor stator or a pump including creating acomputer model of a stator or pump; loading the model into an additivemanufacturing apparatus; and operating the additive manufacturingapparatus to produce a physical replica of the model.

Embodiment 17

A downhole system including a mud motor stator or a pump, the stator orpump being as defined in any prior embodiment.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Further, it should further be noted that the terms “first,”“second,” and the like herein do not denote any order, quantity, orimportance, but rather are used to distinguish one element from another.The modifier “about” used in connection with a quantity is inclusive ofthe stated value and has the meaning dictated by the context (e.g., itincludes the degree of error associated with measurement of theparticular quantity).

While the invention has been described with reference to an exemplaryembodiment or embodiments, it will be understood by those skilled in theart that various changes may be made and equivalents may be substitutedfor elements thereof without departing from the scope of the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope thereof. Therefore, it is intendedthat the invention not be limited to the particular embodiment disclosedas the best mode contemplated for carrying out this invention, but thatthe invention will include all embodiments falling within the scope ofthe claims. Also, in the drawings and the description, there have beendisclosed exemplary embodiments of the invention and, although specificterms may have been employed, they are unless otherwise stated used in ageneric and descriptive sense only and not for purposes of limitation,the scope of the invention therefore not being so limited.

What is claimed is:
 1. A mud motor stator or a pump comprising: atubular outer portion; a number of lobes extending radially inwardlyfrom the tubular outer portion, at least one of which comprises askeletal structure.
 2. The stator or pump as claimed in claim 1 whereinthe skeletal structure consists of an operating portion of the at leastone lobe.
 3. The stator or pump as claimed in claim 1 wherein theskeletal structure comprises one or more ribs.
 4. The stator or pump asclaimed in claim 3 wherein the one or more ribs extend to connect to anoperating portion of the at least one lobe.
 5. The stator or pump asclaimed in claim 1 further comprising material property changes in areasof the stator constructed of the same material.
 6. The stator or pump asclaimed in claim 5 wherein the material property is compliance orresilience.
 7. The stator or pump as claimed in claim 1 wherein thetubular outer portion and the number of lobes include surfaces andwherein at least a portion of those surfaces is conditioned.
 8. Thestator or pump as claimed in claim 7 wherein the surface configurationis conditioned to exhibit a diamond shaped pattern
 9. The stator or pumpas claimed in claim 7 wherein the surface configuration is conditionedto be wavy.
 10. The stator or pump as claimed in claim 7 wherein thesurface configuration is conditioned to exhibit at least one of groovesand bumps.
 11. The stator or pump as claimed in claim 1 wherein theskeletal structure is asymmetric and having a load side and a seal side,and a sealing material that is thicker at the seal side than it is atthe load side.
 12. The stator or pump as claimed in claim 1 wherein theskeletal structure is asymmetric and having a load side and a seal side,and a sealing material that is the same at the seal side as it is at theload side.
 13. The stator or pump as claimed in claim 1 wherein theskeletal structure defines a pathway through the stator for one or moreof fluid and conductors.
 14. A method for producing a mud motor statoror a pump comprising: placing material and bonding the material togetherin a pattern dictated by the design shape of the stator or pump.
 15. Themethod as claimed in claim 14 wherein the bonding is by direct metallaser melting.
 16. A method for producing a mud motor stator or a pumpcomprising: creating a computer model of a stator or pump; loading themodel into an additive manufacturing apparatus; operating the additivemanufacturing apparatus to produce a physical replica of the model. 17.A downhole system including a mud motor stator or a pump, the stator orpump being as defined in claim 1.